081: tallinna uue raekoja konkursitöö

summary: an entry in the 2009 competition for the new town hall of tallinn, done by the austrian / portuguese practice zinterl architekten. titled «green verve», the project was considered to be of great professional quality and functionally well thought through, although visually resembling too much to a sports facility. the jury also made comments on its lavish use of open space, which is ironically one of the main ideas and best feats in this project. full description to follow after an intro in estonian.

_reactivate a remote plot as starting point for the further urban development._improvement of the relationships between city-center and waterfront._expansion of the ensemble of the tallinn city hall and the cultural couldron with a landmark._consideration of the culteral heritage surroundings._construction of an unique common building for the different administration-facilities._enhancement of functional processes and increase of energy-efficiency.

solutions:

_creation of an emblematic building for the city administration._new arrangement of the urban context, e.g. public squares and roads and path network._formal integration into the surroundings with simultaneous retention of an autonomous identification._establishment of an independent architectural object spatially integrated in the environment._preservation of urban prospects due limitation of building height._establishment of an open and transparent building with simultaneously high weather protection._integration of technical and functional courses in a individual big form.

concept:

development of the urban construction of tallinn has always been very closely related to the development of sea and ports. thus the new government building also orientates itself towards the nearby green waterfront. in the interplay with the special situation the architectural proposal results from the innovative formation at the interface between city and the open space. the exceptional form is however not only pure attraction, it makes also a highly economic utilization possible.

the idea comes from the nature and describes a curved landscape. being more a sculptural object than a building, it takes regard to the monumentality of the city hall and the proximity to the industrial cultural cauldron. the dynamic shape mediates protection and security. it takes consequently the formal elements of the city hall, but interprets them in a current manner.

the building is conceived as house in a house. a massive comb-shaped part ist covered by a lightweight roof. the glazed sides offer a great view on the cultural heritage on both sides. together with the new administration building of the tallink company and the stairways of the city hall a new urban place is created.

beneath the great roof are nine trapeze-shaped winter-gardens. their function is to create a buffer zone between the inner building and the outside-area. they also widen the outside moreover optically and let the exterior run into the building. these partially green areas can be differently treated concerning their atmosphere and themes. the distinction of these interior spaces offer orientation and identification for employees and visitors. between the two façade-layers a clima-buffer with sound-protection skills is formed. it allows to aerate the offices and reduce the heating costs consequently.

in the yards disturbing influences like rain, wind, noise and emissions are eliminated so that horizontal sun-protection also becomes possible outside in a high-rise building. moreover, the building can probably be operated without use of technical air-conditioning.

ten trapeze-shaped office-fingers that touch the outside skin of the building come from the communication-spine in the middle. five stair-cores, each for two sections, lie directly at the main-axis, provide short ways and good attainability of each individual area. two staircases drive into the most uppermost levels with decrease inferior public-traffic. the curved form of the roof, that formally appears separately from the structure under it, creates big green terraces, that serve for communication and recreation.

functions:

the wintergardens serve as main-entrances to the new administration-building. the lobbies are forming enlivened and green "display windows", that are not only perceived as attractive eye-catchers at day and night, but are also agreeable atmospheres for the employees in the house.the four yards facing east are intended for the public audience. the west situated, smaller yards are the accesses for the employees and the separated entrances of public related departments. also the above ground parking, the delivery, the entrance for the parking-garage and the drive-up are here.

the public area on the ground floor can be opened on demand into a big interrelated multi-functional space, for example for bigger events or exhibitions. the city-archive which is at the end of the communication-spine has also an independent access northwards.

further archive-areas are in the basement and can be reached directly by three staircases from the departments in the upper floors. in the south the parking-garage stretches partially under the new city square. an area for technical equipement is situated centrally and distributes installations over one lengthwise proceeding technology-spine. the first floor is completely intended for the city office. in the northern part, an event-area and study-zones are connected by a great void with the city-archives under it.

basement floor.

ground floor.

in the further upper floors the different departments are accommodated without losing their individual autonomy. the organisation in the comb-structure allows in ideal manner to offer different office-structures, from the singles-office as far as to the open-plan office. consequently a flexible division and sustainable utilization is guaranteed. the width of the house makes it possible to order archives or printer-areas in the inner communication-zones as well as kitchenettes and meeting points. the huge open spaces with freestanding furniture create a generous work-atmosphere.

the green terraces at the ends of the corridor serve as additional communication-zones as well as locations for events and recreation. all these aspects follow the claim to create a modern building, offering space for the communication between the citizens of tallinn and their officials.

1st floor.

2nd floor.

3rd floor.

4th floor.

5th floor.

6th floor.

technological concept:

an effective sun-protection outside the office-spaces prevents the penetration of unintentional heat in the summer. the undisguised concrete-ceilings provide storage capacity for heating and refrigeration, a balance of the inner climate. conventional radiators should be mainly avoided. aim in the course of the planning was to take advantage of the geometry of the building with utilization of regenerative energies and to minimize energy demands and their required technology.

beside the energetic advantages, the winter gardens offer a high quality of abidance giving space for special events like exhibitions and parties. the ten huge green-areas and the terraces provide a harmonic balance between the working world and the nature. working places got the experience of the nature from each desk, so that the highest claims for a modern working-world are fulfilled.

principal structures:

the clear formal attitude of the building is seen in the inside, and above all, in its constructive structure. the building consists essentially of two elements. the structure of the office-comb is produced with reinforced concrete: flat-slabs lie on ferro-concrete supports with constant grid and an economic span. the pillars lead into the basement without displacement. the staircases are also a structural element. the construction-system is conclusively and without constructive peculiarities from below to the top. the separation of construction and facade allows prefabrication of the facade-elements already during the preparation of the structural work.

the structure of the roof is produced with an gluelam-trusses framework that can partially be produced in prefabrication. it is supported by v-shaped steel-bearings along the outside-façades. loads are derived additionally in the interior by steel-concrete supports extending to upward.

the glass shield cladding the great space is proposed as windtight transparent glazed skin with double thermal insulating glass. the façade construction elements consist of adjustable flat stainless steel posts, adapting to the building geometry. the glazing joints are designed as compact inside glass fixings systems in order to provide a fair-faced and smooth façade surface. these few construction elements, stainless steel posts, stainless steel glass connections to the sub-structure, steel bracket connections to the gallery, represent a highly evaluated low-tech façade construction, efficiently and precisely answering the geometrical and technical requirements.

economical considerations:

the compact design and the prefabricated façade-elements provide creatively and functionally an efficient preparation of the building. the minimization of the simple corridors in the combs save space in favor of the greater communication-mall, that serves as main entrance. leaving the public areas in the ground floor avoid huge lobbys in the upper floors. fire protection-sections are easy to realize. optional office-areas are attainable in short way.

finishing materials:

the roof consists of several materials. in the southern area, it is spoiled with sheet metal-plates and in the upper area, photovoltaics and solar-collectors are installed. in the flat area in the northern part a green roof is intended. the longitudinal-façades are conceived as heat-absorbing double-glazing. for the interior-façades are intended horizontal glass-sheets with single-glazing. they stay on a steel-concrete-parapet and can be opened manually for natural ventilation.

the grounds in strongly frequented areas are executed in flagstones, the office-areas get a resistant and sound-absorbing carpet flooring. the slabs, so far they used for thermal concrete core activation, keeps the concrete-character, the other ceilings and walls gets a finery-layer as well as paint. sound-protection is regulated individually on demand with sound-protection-sails. doors are executed in wood, office-dividers get a clearstory at ceiling-height.

environmental sustainability and building efficiency:

because the dimension of the competition-scope merely the essential parameters with influence to operational costs are listed as follws. beside all technical parameters it is essentially necessary that people feel cozy in all parts of the building.

the load on the environment is mainly influenced by how much energy a building requires. here, attention to early coordination of the façade, individual parts of the building, thermal qualities of the building and the cooling and heating systems is important, particularly:─optimum of heat insulation and sun-shading.─reducing solar loads by optimizing the use of daylight. ─use of solid building materials (storage mass). ─night-time cooling in summer for example with thermal concrete core activation (systems of water pipes in concrete ceilings).─use of buffer zones.